Back in the olden days when the Matching Gifts Symposium existed and we published a series of matching gift best practices books, we advocated FOR giving spouses equal matching gift credit. One of the rationales was that many employers offer matching donations for employees' spouses. The reality is that when a gift comes from a married individual, it is essentially a gift from both (joint ownership), unless directed otherwise.
Giving joint soft credit also eliminates the need for some donors telling you to "split" the legal gift so that both spouses get equal credit.
I am traveling in the UK but will see if I can find the aasp soft credit best practices document from several years ago and see if it addressed this topic.
John
John Taylor Principal, John H. Taylor Consulting, LLC 919.816.5903 Big ideas; small keyboard